Biomaterials are being used with increasing frequency for tissue substitution, such as for joint replacements and artificial organs. Tissue integration onto or into these biomaterials enhances long-term biocompatibility of these devices, and requires a form of eukaryocytic adhesion or compatibility with possible chemical integration to an implant surface. However, in what has been characterized as a “race for the surface”, bacterial cells are known to compete with tissue cells for colonization onto the surfaces of such biomaterials. If bacterial cells are successful in colonizing an implant surface, devastating infections can occur which can require subsequent surgeries, or even result in sepsis and death, especially in immunosuppressed patients.
In “Biomaterial-Centered Infection: Microbial Adhesion Versus Tissue Integration”, by Anthony G. Gristina, Science, Vol. 237, pp. 1588-1595 (1987), the author discusses the details of biological attraction and adhesion to various biomaterial implants and concludes that an optimum mechanism for preventing bacterial infection on such surfaces would be to develop biomaterial surfaces which encourage rapid eukaryocytic colonization of the surface, so as to impart the benefits of naturally derived antibacterial mechanisms produced by the living cells adhered to the surface.
There is an ongoing need for polymer-based structures having improved adsorption of biologics, e.g., proteins. Such structures can be suited for use in various applications, such as medical applications, e.g., medical diagnostics. It is especially desirable to provide structures whose surfaces have a specific, finely-tuned adsorption of biological materials.
U.S. Pat. No. 5,246,451 discloses a vascular prosthesis made by coating a vascular graft material such as polyethylene terephthalate plasma coated with a fluoropolymer (PTFE) which is then treated with a plasma in a non-polymerizing gas atmosphere, e.g., oxygen, to improve biological entity binding to the fluoropolymer. The products of this disclosure rely on plasma treatment to improve protein binding and lack modified topography.
U.S. Pat. No. 7,195,872 teaches providing substrates of high surface area with structural microfeatures that provide access to fluids and components therein. The substrates can be prepared by molding, embossing, photoresist techniques and can also be treated by etching, e.g., with argon, oxygen, helium, chlorine, SF6, CF4, and C4F8 gases. Surfaces can be modified by chemical treatments or radiative treatments, e.g., plasma treatment in gases. The reference emphasizes topography alone to bind proteins, or alternately, additional treatment with oxygen plasma to etch the surface and ammonia plasma for grafting amine groups on the surface.
U.S. Patent Publication No. 2006/0154063 discloses a composite nanofiber construct comprising: at least a first nanofiber comprising at least a polymer and at least a calcium salt nanoparticle, wherein the ratio of polymer to calcium salt nanoparticle is between the range of 99:1 and 10:90 weight percent; and at least a second nanofiber comprising at least a polymer and at least a calcium salt nanoparticle, wherein the ratio of polymer to calcium salt nanoparticle is between the range of 100:0 and 70:30 weight percent. Hydrophilicity of the nanofibers is enhanced by plasma treatment, which lead to good adhesion and growing of cells.
U.S. Patent Publication No. 2008/0241512 discloses a chemical vapor deposition method of depositing layers of materials to provide super-hydrophilic surface properties, or super-hydrophobic surface properties, or combinations of such properties at various locations on a given surface. The invention also relates to electronic applications which make use of super-hydrophobic surface properties, and to biological applications which make use of super-hydrophilic surface properties.
It would be desirable to provide a highly hydrophilic surface structure which does not require a separate treatment step to enhance its hydrophilicity.
It would be further desirable to provide wettable polymer-based structures of substantially fixed topography having controllable adsorption of biologics, e.g., proteins, by adjusting characteristics of a substrate to provide a topography of enhanced surface area that is relatable or proportional to the surface adsorption of a biologic material.